Dredgen Yor was a Hunter[1] and the last known carrier of the exotic Hand Cannon Thorn,[2] which he claimed to have created himself.[3] He was once regarded as a heroic Guardian[4] and was unstoppable in the Crucible,[1] but he delved into the dark mysticism of the Hive and eventually turned against his fellow Guardians,[2][4] murdering Pahanin Errata,[1] Thalor,[5] and at least three other people.[3] Destiny wiki for ya